Appetite regulation is independent of the changes in ghrelin levels in pregnant rats fed low-protein diet

Abstract

Gestational protein restriction causes hypertension in the adult offspring. Very little is known about the food intake regulation and ghrelin signaling in pregnant dams fed a low-protein (LP) diet. We hypothesized that diet intake and ghrelin signaling are altered in pregnant rats fed the low-protein diet. Sprague–Dawley rats were fed a control (CT) or LP diet from Day 3 of pregnancy. Diet intake and body weight were monitored daily. Expression of ghrelin production-related genes in the stomach and appetite-related genes in the hypothalamus was analyzed by real-time PCR. Plasma levels of total and active ghrelin, growth hormone and leptin were measured by ELISA. Main results include: (1) Daily diet intake was greater in the LP group than in the CT group in early pregnancy, but substantially lower in late pregnancy; (2) Daily gain in body weight was substantially lower in the LP group in late pregnancy; (3) Expression of ghrelin production-related genes in the stomach and plasma total ghrelin levels were increased in LP group in late pregnancy; (4) Plasma active ghrelin levels were elevated in the LP group at mid-late pregnancy, but growth hormone and leptin levels were uncorrelated with active ghrelin in late pregnancy; and (5) Hypothalamic expression of ghrelin-stimulated genes in LP rats was unassociated with the changes in both plasma ghrelin levels and the diet intake. Taken together, the appetite in LP rats is greater in early pregnancy but reduced at late pregnancy, possibly due to ghrelin insensitivity in appetite regulation.

Blunted hypothalamic ghrelin signaling reduces diet intake in rats fed a low-protein diet in late pregnancy

“…2012a, 2012b) and consumed a significantly lower amount of diet during later period of pregnancy (Gao et al. ). Offspring from mothers fed LP diet during gestation have been shown to become hypertensive when they become adults (Langley‐Evans et al.…”

“…More information about these diets were described in details in our recent publication (Gao et al. ).…”

“…Procedures and reagents for reverse transcription and real‐time PCR were described in detail in our recent report (Gao et al. ).…”

“…Recently, we found that diet consumption by rats fed a LP diet was lower during late gestation compared to that by rats fed normal protein (CT) diet (Gao et al. ). As a consequence, this reduced diet intake exacerbates nutritional insufficiency during late pregnancy when fetal growth is exponential.…”

“…Our recent study suggested that the plasma levels of ghrelin are not associated with the changes in the diet intake in pregnant rats fed a LP diet, as elevated levels of plasma ghrelin failed to stimulate the diet intake during late pregnancy (Gao et al. ). This is inconsistent with the known diet intake stimulating function of ghrelin.…”